1. Field of the Invention
The present invention relates to a method and a device for driver assistance by generating lane information for supporting or replacing lane information of a video-based lane information device.
2. Description of Related Art
Driver assistance systems for motor vehicles, in particular driver assistance systems for lateral guidance, exist for increasing comfort and driving safety. Currently, advanced driver assistance systems for lateral guidance are in development or at the preproduction stage, which warn the driver against an unintended departure from the host vehicle's own driving lane (lane departure warning—LDW) or to assist the driver in maintaining the host vehicle's own driving lane while driving (lane keeping support—LKS). The requirements of these systems as regards the accuracy and quality of the lane information are considerably higher than those of driver assistance systems for longitudinal guidance (ACC).
Driver assistance systems for lateral guidance usually operate using a video sensor device. For example, a video camera periodically records an image of the road in front of the vehicle, and the drivable markings are detected in this image by suitable algorithms and are described by a mathematical model. Such video-based sensor systems require an unobstructed view of the lane markings. If the view is entirely or partially obstructed, as is frequently the case in traffic jam situations by vehicles preceding in close proximity, then no or only incomplete lane information is available. Likewise, video-based lane detection often fails if the lane marking is soiled or the paint of the lane marking is old or poorly visible or if there exists no lane marking at all.
A modern motor vehicle usually has a steering angle sensor, a yaw rate sensor and acceleration sensors, by which it is possible to estimate or extrapolate the current vehicle movement using a vehicle model. In particular, using the yaw rate signal of the yaw rate sensor it is possible to determine at any time the curvature of the course which the vehicle is currently traveling.
Navigation devices for motor vehicles have a device for determining the vehicle position, which is normally GPS-based, by which the current position of the vehicle may be determined with an accuracy of a few meters.
Systems for vehicle-to-vehicle communication are currently in development. An example of this is the “Car-2-Car Communication Consortium” (C2C CC), to which the automobile manufacturers Audi, BMW/Mini, DaimlerChrysler, Fiat, Renault and Volkswagen belong. In addition to working out an open industry standard for the communication between vehicles and between vehicles and infrastructure facilities at the European level, the “C2C CC” is supposed to advance the allocation of a radio frequency required for this purpose and develop and test appropriate radio systems.
One exemplary embodiment for the vehicle-to-vehicle communication is the specific transmission of information to other drivers. If a vehicle gets into a critical situation, for example, such as a traffic jam, fog, icy roadway, an accident or the like, it transmits respective information to all affected road users in the immediate vicinity of the danger spot. The following traffic is warned in time and is able to react appropriately to the situation. In such a spontaneous information network, each vehicle may take on the role of transmitter, receiver or router. This results in the formation of a chain of information similar to a relay race. By such a “multi-hopping” method, the information may be passed on over a larger distance. The data exchange between the vehicles is realized using “ad hoc networks”. These short-distance connections build up spontaneously between vehicles as needed, are self-organizing and require no external infrastructure for this purpose. The WLAN technology known from computer systems forms the technological basis for this purpose.
Additionally there exist methods and devices for ascertaining lane course data from detections of preceding vehicles by object-detecting sensors such as e.g. radar, lidar or video, as disclosed, for example in DE 103 54 650 A1 or DE 103 49 631 A1. These sensors, however, have a very limited detection range tailored to their proper task. Furthermore, these sensors detect all types of objects, which requires an additional discrimination between objects relevant for lane support and objects not relevant for lane support.
Digital maps for vehicle navigation systems have a resolution and an accuracy that is sufficient for the navigation function, but that is by far not sufficient for future driver assistance systems, for example, for lateral guidance in the driving lane. Furthermore, digital maps for vehicle navigation systems, which are currently normally stored on storage media such as CDs or DVDs, for example, are fundamentally obsolete at the time they are in use since they store only the data record that was valid at the time of their production.